[BUG] Don't get the comment with preview url on PR merged

### Action config

```
on:
push:
branches: [master]
...
- uses: FirebaseExtended/action-hosting-deploy@v0
with:
repoToken: "${{ secrets.GITHUB_TOKEN }}"
firebaseServiceAccount: "${{ secrets.FIREBASE_SERVICE_ACCOUNT }}"
projectId: ***
expires: 14d
channelID: preview
```

### Error message

N/A

### Expected behavior

To post the comment with preview url.

### Actual behavior

I don't get any comment with preview url for PR merged configuration.